Prosthodontic restorative systems, tools and techniques are well-known in the prior art. For patients missing some or all of their teeth, a dental implant fixture is implanted in a bore made in a patient's jawbone after the gum tissue has been pealed back. The fixture typically includes an internally-threaded socket which receives one or more components used for attaching a permanent dental restoration, such as a tooth.
The various components of prosthodontic restoration are typically driven and tightened with respect to the implant combination or each other using many different drivers or wrenches, one for each type of restorative component. The prosthodontist or surgeon manipulates the drivers manually or through the use of an automatic device. Automatic devices usually include a torque control mechanism to insure that components are tightened to their optimum torque.
Precise and complete tightening of the components in a restoration is often difficult to achieve manually. The surgeon must take care to apply sufficient and consistent torque to these fixtures, screws or bolts, otherwise over-torque can lead to needless pain and rehabilitation, while under-torque leads to loosened components and support resulting in displaced fractures. Components that loosen and back-out of their fittings, require repeated office visits and even additional surgery for retightening. While automatic devices generally overcome this problem, such devices are costly and somewhat cumbersome to use. Moreover, the accuracy of such devices will degrade over time by wear, tear and adverse effects of sterilization.
Small, easy to use tools that ratchet and indicate torque applied to a given workpiece would be useful in the aforementioned fields. Various ratchet wrenches have been invented, and are usually grouped into two types: torsional ratchet wrenches such as the "Dental Implant Wrench," U.S. Pat. No. 5,368,480 issued to Balfour et al., and ratchet pawl wrenches such as the "Ratchet Handle with Torque Adjustment," U.S. Pat. No. 5,557,994 issued to Nakayama.
Other art, such as with the "Torque Control Ratchet Wrench," U.S. Pat. No. 5,337,638 issued to Coss et al., simply teaches a handle breaking out of alignment with a cam member when a torque limit is reached. This feature creates a requirement for a large set of such tools, because a single tool does not cover more than one torque value.
Earlier art, such as with "Improvements In or Relating to Torque-Indicating Wrenches," U.K. Patent No. 825,282 to Prosser, teaches a semi-circular rotating pawl with two notches as a way to engage a ratchet wheel. A termination member develops the torque which is then transmitted through a torque-transmitting lever to a torque-reaction spring.
In the instant invention, the concept of using a flexible beam extending from a pawl to both ratchet and sense torque encountered during engagement and rotation of a workpiece is believed to be novel.
There is therefore a need to provide a new tool for driving components used in a dental prosthodontic restoration and orthopedic reconstruction that overcomes the problems of torque application and the other issues of the related art.
It is an object of the present invention to provide a single tool for manually driving components of a dental restoration system that precisely and reproducibly tightens components to a specified, measurable torque in a simple and cost effective way.
It is another object of the present invention to provide for an indication of graduated torque values during the application and measurement of torque.
It is still another object to provide a tool for driving components in a dental restoration system that can be used with a variety of different makes and styles of component parts.
It is yet another object of the present invention to provide a means for both ratcheting and sensing of actual torque during insertion of implant devices, along with the parallel diagnostic value of such torque measurement.
It is yet another object of the present invention to provide a robust tool with the ability to withstand large torque overloads without damage to the tool, or its ability to transduce and indicate torque.
It is still yet another object of the present invention to provide for an inexpensive torque indicating tool that is simple, readily cleanable, user-friendly, requires minimal maintenance and calibration, and that can be driven manually (such as by ratchet) or automatically (such as by a powered handpiece).
It is still yet another object of this invention to provide this torque indicating tool in a handheld, easy to use wrench format, that is functionally tolerant of biological fluids, capable of withstanding chemical and steam sterilization processes and yet retain precision in measuring torque.
The aforementioned background has outlined some of the more pertinent objects of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention as will be described. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the following illustrations, and the written disclosure of the Detailed Description of the Invention.